The Collaborative International Dictionary of English v.0.48:

Cockspur \Cock"spur\, n. (Bot.)
   A variety of Crat[ae]gus, or hawthorn (Crat[ae]gus
   Crus-galli), having long, straight thorns; -- called also
   Cockspur thorn.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cockspur thorn
    n 1: eastern United States hawthorn with long straight thorns
         [syn: cockspur thorn, cockspur hawthorn, Crataegus
         crus-galli]